Radio receiving system



Jan. 3, 1933. w. w. MACALPINE RADIO RECEIVING SYSTEM Filed April 12, 1952 Al CZMBQMEL INVENTOR I William W Manalp'ma BY ATTORNEY Patented Jan. 3, 1933 PATENT OFFICE WILLIAI'I. WALTER MACALIINE, OF EAST ORANGE, NEJV JERSEY RADIO RECEIVING SYSTEM Application filed April 12,

My invention pertains in general to radio receiving systems and specifically relates to a universal receiver for receiving programs from a variety of sources.

One of the objects of my invention consists in providing a radio receivingsystem having meals for producing diiierent resonance response characteristics for the reception of signals from different sources. Another object comprises providing a receiving system for the reproduction of a program from a plurality of diiierent sources under control of a common switching'system for affecting circuits individually connected with a plurality of electron tubes.

A further object consists in producing a radio receiving system employing a plurality of electron tubes and circuits connected therewith associated with a commonly controlled switching system for simultaneously altering the constants and connections of said circuits and controlling the voltage supplied to cer tain of said tubes for the efiicient reproduction of programs from diilerent program "2 sources.

T accomplish these and other desirable objects in a novel radio receiving system in which resonant circuits having adjustable response characteristics are controlled by a system of switches operatively connected with electron tubes for varying the voltage supply thereto in a predetermined manner whereby the radio receiving system as a whole is rendered effective for the reproduction of pro- 9 grams from local broadcasting stations, distant broadcasting stations. or from a phonograph recordings.

In the drawing which accompanies and forms a part of this specification:

Fig. 1 is a diagrammatic representation of one embodiment of the radio receivingsystem of my invention; and

Fig. 2 is a graphical representation of typical response characteristics brought about in the operation of the radio receiving system represented in Fig. 1.

Referring to the drawing in detail, an antenna 1 and ground 2 comprise a space radio r energy collecting system connected with inductance 3 which is inductively coupled with 1932. serial No. 604,?1 0.

inductance 4. The inductance 4 is connected through a variable condenser 16 to ground and also through inductance 11 to a movable switch blade 6 which may engage with any of three contacts 12, 13, or 14. Contact 12 is connected through a fixed capacitance and thence to ground. The contact 14 is connected through another fixed capacitance 21, which is an equivalent of the fixed capacitance 20, to ground. The inductance 11 is coupled to. inductance 15, which forms a series circuit with condensers 17 and 20.

Connections are provided, as shown, from the inductance 15 and condenser 17 to the control electrode and cathode of an electron tube 22 of the screen grid type. The anode or output circuit of the tube 22 includes an inductance 26 coupled with an inductance 27 which is in circuit with a variable condenser 18. and fixed capacitance 30. The. inductance 27 and condenser 18 are connected with the control-electrode and cathode of an electron tube 23 of the screen grid type. A sourceof voltage 31 connects to switch blade 7. The switch blade 7 is movable for engagement 7 with any of three contacts 32, 33, and 34:. A source of voltage 35 acts through a resistance 36'to apply a negative potential to the screen electrode of the tube 23. A condenser 37 is provided as shown between the screen electrode and cathode. A connection is provided from the screen electrode to contact 34. The source of voltage 31 provides the normal positive potential or G bias for the screen electrode of the tube 23. When the switch blade 7 is in the position shown in the figure the negative potential applied to the screen electrode of tube 23 by the source of voltage 35 will render the tube 23 inoperative. However, when the switch blade 7 is in engagement with the contact 34, the potential of the source of voltage 31 will overcome the effect of the source of voltage 35 and apply a positive potential of the correct magnitude to the screen electrode of tube 23 whereby the tube 23 becomes operative for amplification purposes. The method of rendering the tube 23 inoperative by applying a negative potential to the screen electrode is particularly advantageous inasmuch as the inter-electrode capacitance of the tube is unaffected and the matching of the tuning condensers is therefore undisturbed. This is particularly important in receiving systems of the class to which my invention appertains. A further advantage resides in that no switching elements are utilized in the high potential side of the radio frequency circuits.

The anode or output circuit of the tube 23 includes an inductance 39 coupled to inductance 40. One side of the inductance 40 is connected with a variable condenser 19 and the other side is connected through a movable switch blade 8 which may engage with any of three contacts 41. 42, and 43. The contact 43 is connected through inductance 44 and capacitance 45 to ground. The inductance 40 and condenser 19 are connected through capacitance 46 to the control electrode of another electron tube 24 of the screen grid type. A connection is provided from the control electrode of the tube 24 to a movable switch blade which may engage with any of three contacts 47, 48, or 49. A connection is provided from contact 48 to an audio frequency autotransformer coil 51 having a connection to electrical phonograph pickup 50. A source of biasing voltage 25 is provided in circuit with the contact 48. The anode or output circuit of the electron tube 24 includes a resistance 52 connected with a movable switch blade 10 which may engage with any of three contacts 53. 54, and 55. The contacts 53 and 55 are connected to a source of anode voltage 56, while the contact 54 is connected to an additional source of anode voltage 57 in series with the source of anode voltage 56. The output circuit from electron tube 24 also includes connections through the capacitance 58 to an audio frequency amplifier 59 and translating device comprising a loud speaker 60.

Other elements and connections shown in the diagram of Fig. 1 are of a conventional character and well-known in the art. It will be noted that. for simplicity of description, batteries have been shown as sources of voltage supply whereas in practice a power pack and voltage dividers are employed for supplying the proper potentials. The negative C grid biasing voltages for the tubes shown in Fig. 1 are applied through resistances which have no appreciable efiect on the tuned circuits.

The movable switch blades 6-1O are mechanically interconnected by an insulating bar whereby all of the switches can be moved in unison to a desired position under control of a suitable knob mechanically connected with the bar 5. All of the condensers 16 to 19 have a common mechanical control as indicated by the dotted interconnecting line.

lVhen it is desired to receive the signals from broadcasting stations geographically lo cated near the receiving system and known as local stations, the bar 5 is moved to the left whereby the switch contact blades (5 to assume positions in engagementwith the contacts 12, 32, 41. 47, and 53, respectively. The condensers 16 to 19 are then adjusted by their common control system to select a desired local station. The space radio energy from antenna 1 and ground 2 will then set up currents in the first tuned circuit or transfer circuit which now comprises inductance 4. condenser 16. inductance 11. switch 612, and condenser 20. The second tuned circuit comprises inductance 15. condenser 17, and condenser 20, the second circuit being coupled to the first circuit by means of condenser and the mutual inductance of inductances 11 and 15. The condenser 20 and inductance 11, in conjunction with the other parameters of the circuits. are adjusted to produce a bandpass transmission characteristic such as depicted by the dotted line curve of Fig. 2, and which will be substantially constant over the entire broadcast frequency range.

The voltages across condenser 17 are impressed on the control electrode of the tube 22. The output circuit of tube 22 induces electromotive forces in the inductance 27 which forms part of a tuned circuit including condenser 18 and condenser 30. The tuned circuit 18-2730 is coupled, by means of condenser and the mutual inductance of inductances 27 and 28 to another tuned circuit comprising condenser 19, inductance 40. switch 841, inductance 28 and condenser 30. The voltages across condenser 19 are then directed through condenser 46 to the control electrode of tube 24 which serves as a detector. The tube 23 is now rendered inoperative due to the negative potential applied to the screen electrode thereof by the source of potential acting through resistance 36. The tube 24 receives anode voltage from the source of voltage 56. In the present position of the switch bar 5 the incoming signals from antenna 1 will be amplified at radio frequencies by tube 22 and detected by tube 24 for subsequent amplification by amplifier 59 and program reproduction by loud speaker 60.

For the reception of programs from a remote source such as a distant station, the bar 5 is moved to the extreme righthand position whereby the switches 6 to 10 are in engagement with contacts 14, 34, 43, 49, and 55. In this position of the switches the incoming signalling energy traversing inductance 3 causes currents to traverse a first tuned circuit or transfer circuit which is now composed of inductances 4 and 11 and condensers 16 and 21 together with switch 6 14. The coupling with the second tuned circuit. comprising inductance 15 and condensers 17 and 20, is now only through the mutual inductance of the indnctances 11 and 15,

which coupling is less than the coupling obtained when the switch bar 5 was in the left hand or local position. The response char acteristic of the tuned circuits of the radio receiving system for distant reception now is in the form of the full line curve of Fig. 2 which is indicative of greater sensitivity and narrower band width.

Tube 22 amplifies the high frequency currents in the second tuned circuit whereupon the inductance 26 in the output circuit of tube 22 induces amplified voltages in inductance 27. Inductance 27 forms part of the tuned circuit which includes capacitance 30 and condenser 18. The tube 23, then, serves as a high frequency amplifier since the source of voltage 31 is connected through switch 7-34 for applying a proper positive potential to the screen electrode of tube 23 which over comes the negative potential otherwise supplied by source of voltage 35. The signals amplified by tube 23 act through inductance 39 to induce amplified voltages in inductance 40 which forms part of a tuned circuit now including condenser 19, condenser 45, and inductance 44. The tube 24, receiving anode voltage from the source of voltage 56, now serves, as before, for detecting the amplified highfrequency currents for subsequent amplification by the audio frequency amplifier 59 and program reproduction by the loud speaker 60. The additional use of tube 23 and the change in the character of the tuned circuits produces increased sensitivity for distant reception, together with a narrow ing of the receiving band width which is very desirable for distant reception.

For reproduction of recorded programs from the electrical pickup 50, the switch 5 is moved into a position in which the switch blades 6-10 respectively engage the contacts 13, 33, 42, 48, and 54'. In this position of the switch bar 5 the first tuned circuit including inductance 11 is open circuited at contact 13 and the battery 35 applies a negative potential to the screen electrode of tube 23 which will render the same inoperative. The source of voltage 25 serves as a biasing potential to alter the operating characteristic of tube 24 from that of detection to that of amplification whereby the tube 24 serves as an audio frequency amplifier under control of pickup 50. At the same time, the switch '10, being in engagement with contact 54, applies the additive value of the sources of voltage 56 and 57 to the anode circuit of tube 24 for increased audio frequency amplification. The radio recciving system now serves as a phonograph reproducer having an audio frequency system including the tube 24 and amplifier 59 operating under control of pickup device 50 for reproduction of recorded programs by the translating device 60.

The above described system may be extended to include a multi-position switch having, in addition to the local, distant, and phonograph positions, other positions which connect the receiver for the reproduction of programs coming over wire lines by carrier current, local microphone pick-up, or short wave reception. 7

It will now be evident that I have provided a novel form of radio receiving system which provides for the eflicient reception of signals from distant or local stations together with phonograph reproduction for universal pro gram service. My experimentshave proven that the system of my invention is extremely efiicient and practical in its operation for the purposes indicated. Although I have shown a preferred embodiment of my radio receiving system it will of course be obvious that changes can be'made therein without departing from the intended scope of my invention.- I do not therefore desire to limit myself to the foregoing except insofar as may be pointed out in the appended claims.

What I claim as new and original and desire to secure by Letters Patent of the United States is:

1. A radio receiving system comprising, a pluralityof electron tubes, a plurality of tuned circuits, switching means for rendering certain of said tuned circuits operatively in circuit with certain of said tubes whereby received signaling energy is amplied to a smaller or greater extent depending upon the connections of said tuned circuits with said tubes, other switching means for changing the transmission response of said tuned circuits for receiving a narrower or wider band width of signal frequencies and means for controlling said switching means to cause said receiving system to produce greater amplification of a narrowerband of frequencies of signals received from certain stations or to produce smaller amplification of a wider band of frequencies from certain other stations the selection of which depends upon the tuning of said tuned circuits.

2. A radio receiving system comprising, a plurality of electron tubes having input and output circuits, a plurality of tuned circuits, each one of which is connected with the input circuit of one of said tubes, switching means for connecting one of said tuned circuits with another of said tuned circuits to by-pass one of said tubes, means controlled by said switching means for applying a negative potential to said tube so by-passed to render the same inoperative for the reception of signals, other switching means for changing the transmission response characteristics of said tuned circuits to govern the width of the band of frequencies of signals received by said receiving system, and a common control element for moving said switching elements.

3. A-radio receiving system comprising, a signaling energy collecting system, a plurality of electron tubes each having input and output circuits, each of said input cir-' cuits being tunable to signals at desired frequencies, said tubes being arranged in tandem order, switching means for operatively connecting the tunable input circuit of one of said electron tubes with the tunable input circuit of the succeeding electron tube for causing signals to by-pass one of said tubes, means under control of said switching means for applying a negative potential to said tube so by-passed to render said tube inoperative for the transconductance of signals derived from the tunable input circuit connected therewith, a tunable transfer circuit for transferring energy from said energy collecting system to the tunable input circuit of the first of said electron tubes in tandem order, and other switching means for altering the coupling between said transfer circuit and said tunable circuit to render said receiving system responsive to signaling energy at frequencies within controlled band widths, and common means for controlling said switching means to render said receiving system most eflicient for reception of signaling energy from local or distant stations.

4. A radio receiving system comprising, a signaling energy collecting system, a plurality of electron tubes having input and output circuits, each of said input circuits being tunable to signals at desired frequencies, said tubes being arranged for tandem operation, commonly controlled means for changing the tuning of said circuits, switching means for operatively connecting the tunable input circuit of one of said electron tubes with the tunable input circuit of the succeeding electron tube for causing signals to by-pass one of said tubes, means for applying a negative potential to said tube so bypassed to render said tube inoperative for the transeonductance of signals derived from the tunable input circuit connected therewith, means under control of switching means for changing the operation of one of said tubes from a detector to an amplifier, a tunable circuit for transferring energy from said energy collecting system to the tunable input circuit of the first of said electron tubes in tandem order, and switching means for altering the coupling between said circuit and said tunable input circuit to render said receiving system responsive to signaling energy at frequencies within controlled band widths and common means for controlling said switching means to cause said tunable circuits to receive signals from distant stations within comparatively narrow band widths for amplification by all of said electron tubes or for causing said receiving system to receive signals from local stations at frequencies within comparatively wider bands for amplification by a fewer number of said tubes, one of said tubes being by-passed.

5. A radio receiving system comprising, a

signaling energy collecting system, a plurality of electron tubes having input and output circuits, each of said input circuits being tunable to signals at desired frequencies, said tubes being arranged in tandem order, a tunable transfer circuit for transferring signaling energy from said energy collecting system to the first of said tunable input circuits in said tandem order, a switch for connecting said transfer circuit in either of two different forms of coupling with said first tunable circuit, a switch for selectively connecting the tunable input circuit of one of said electron tubes with the tunable input circuit of the succeeding electron tube for causing signaling energy to by-pass one of said tubes, means for applying a negative potential to said tube so by-passed, a source of voltage, a switch for applying a positive potential to said last mentioned electron tube to overcome said negative potential applied thereto when said tunable input circuit connected therewith is disconnected from the succeeding tunable input circuit of the succeeding electron tube, a local source of audio frequency currents, a switch for connecting said source of audio frequency currents with a succeeding one of said electron tubes, means under control of a switch for applying voltages to said last mentioned tube to cause said tube to function as a detector for said signaling energy or as an amplifier for said audio frequency currents, and common means for controlling said switches whereby said radio receiving system may function in any one of the following ways: as a system especially adapted for reception of high frequency signalling energy within a predetermined frequency band in which one of said tubes serves as a detector; as a system especially adapted for reception of high frequency signalling energy within a comparatively broader frequency band in which one of said tubes serves as a detector and in which at least one of said tubes is by-passed and is inoperative for amplification purposes, or as a system for the amplification of said audio frequency currents in which the function of said detector tube is changed to that of an amplifier for said audio frequency currents and the preceeding tubes rendered operatively ineffective for the amplification of signals.

WILLIAM lV. MAOALPINE. 

